Objective tests of middle ear function based on the difficulty (impedance) or ease (admittance) of sound flow through the middle ear. These include static impedance and dynamic impedance (i.e., tympanometry and impedance tests in conjunction with intra-aural muscle reflex elicitation). This term is used also for various components of impedance and admittance (e.g., compliance, conductance, reactance, resistance, susceptance).
The branch of physics that deals with sound and sound waves. In medicine it is often applied in procedures in speech and hearing studies. With regard to the environment, it refers to the characteristics of a room, auditorium, theatre, building, etc. that determines the audibility or fidelity of sounds in it. (From Random House Unabridged Dictionary, 2d ed)
Any device or element which converts an input signal into an output signal of a different form. Examples include the microphone, phonographic pickup, loudspeaker, barometer, photoelectric cell, automobile horn, doorbell, and underwater sound transducer. (McGraw Hill Dictionary of Scientific and Technical Terms, 4th ed)
The resistance to the flow of either alternating or direct electrical current.
The visualization of deep structures of the body by recording the reflections or echoes of ultrasonic pulses directed into the tissues. Use of ultrasound for imaging or diagnostic purposes employs frequencies ranging from 1.6 to 10 megahertz.
Recording changes in electrical impedance between electrodes placed on opposite sides of a part of the body, as a measure of volume changes in the path of the current. (Stedman, 25th ed)
A type of impedance plethysmography in which bioelectrical impedance is measured between electrodes positioned around the neck and around the lower thorax. It is used principally to calculate stroke volume and cardiac volume, but it is also related to myocardial contractility, thoracic fluid content, and circulation to the extremities.
A technique of measuring the dielectric properties of materials, which vary over a range of frequencies depending on the physical properties of the material. The technique involves measuring, over a range of frequencies, ELECTRICAL IMPEDANCE and phase shift of an electric field as it passes through the material.

Confirmation of deafness in infancy. (1/154)

AIM: To assess delay in confirming hearing impairment in infants identified by universal neonatal screening and to investigate the causes. PATIENTS: Infants identified from 25 199 babies screened from January 1992 to December 1997. METHODS: A two stage transient evoked oto-acoustic emission test (TEOAE), with a threshold auditory brainstem response (ABR) recording undertaken on those who failed. The screen identified infants with a permanent congenital hearing impairment (PCHI) averaging 40 dBnHL or worse in the best ear. Those with less impairment were also ascertained. The positive predictive value (PPV) of the ABR test and measures of delay between identification and eventual diagnosis were analysed. RESULTS: A targeted PCHI was found in 1.18/1000 neonates. The PPV of the ABR for confirming a targeted PCHI was 100% when the ABR threshold was >/= 80 dBnHL. Nine of 11 infants with this threshold had severe or profound permanent deafness. The delay from ABR to audiological certainty was about 1 month-diagnosis was confirmed around 3 months. There was uncertainty when the ABR was 40-80 dBnHL. The PPV was 60% and 8% when the ABR thresholds were 70 dBnHL and 50 dBnHL, respectively. 85 of 111 infants with ABR thresholds in this range had a temporary conductive impairment. Their early diagnosis depended upon the type and degree of hearing impairment and diagnosis was delayed to about 8 months in these infants. CONCLUSIONS: Hearing impairments identified by universal screening are delayed in all but those with severe or profound bilateral PCHI. This delay can be reduced by applying in early infancy a battery of audiological tests and requires further exploration.  (+info)

Otolaryngological findings in congenital nasolacrimal duct obstruction and implications for prognosis. (2/154)

AIM: To investigate otolaryngological abnormalities associated with congenital nasolacrimal duct obstruction (CNLDO) and their effect on the prognosis. METHODS: 65 consecutive cases of CNLDO were followed up with routine otorhinolaryngological examination with tympanometry. RESULTS: Otitis media with effusion (OME) and uvula bifida were detected in 44.6% and 9.2% of the children, respectively. Medical treatment and probing were less effective in patients with OME (p<0. 05). CONCLUSIONS: OME and uvula bifida are significant anomalies associated with CNLDO and the former has a marked effect on the prognosis. This finding may help to determine the patients who will need further treatment after massage and probing.  (+info)

Tympanometry for diagnosis and treatment of otitis media in general practice. (3/154)

OBJECTIVE: The aim of this study was to evaluate the role of tympanometry for diagnosis, treatment and follow-up of otitis media in general practice. METHODS: The results from otoscopy performed by 40 physicians in general practice in Vejle County, Denmark were combined with the clinical condition and this was recorded as the preliminary decision about diagnosis, treatment and follow-up. Subsequently, tympanometry was performed in 3176 children aged between 1 month and 16 years; a total of 6352 tympanometries. With this added knowledge, a final decision about diagnosis, treatment and follow-up was recorded. The practitioners were trained in performing tympanometry including the interpretation of the results. Simultaneously, they were involved in the establishment of guidelines for diagnosis, treatment and follow-up of otitis media in general practice. The main outcome measures were changes between preliminary and final decisions about diagnoses, treatments and follow-up regimens. RESULTS: Tympanometry was performed successfully in 87.7% of the children, and in 26.4% changes in diagnoses were found. However, tympanometry did not influence the distributions of the main outcome measures in the sample as a whole. Uncomplicated cases were checked in general practice and referrals to specialists were not increased. CONCLUSION: Tympanometry can be performed successfully in general practice after appropriate instruction. In 26.4% of children, the diagnoses were changed, which may result in more appropriate treatment and follow-up. Tympanometry is a clinically relevant supplement to the examination of a child in general practice.  (+info)

Behaviour and developmental effects of otitis media with effusion into the teens. (4/154)

OBJECTIVE: To examine whether behavioural or cognitive sequelae of otitis media with effusion (OME) continue into late childhood and the early teens (11-18 years). SETTING: Data from a large multipurpose birth cohort study: the Dunedin multidisciplinary health and development study. PARTICIPANTS: Around 1000 children from the study. The main independent variable of interest was otological status of the child up to age 9. MAIN OUTCOME MEASURES: Parent and teacher rated behaviour problems, including antisocial, neurotic, hyperactive, and inattentive behaviours, and tests of academic achievement including intelligence quotient (IQ), reading, and spelling were available in a high proportion of the cohort at ages 11 to 18 years. RESULTS: After adjustments for covariates such as socioeconomic status, hyperactive and inattentive behaviour problems were evident as late as 15 years, and lower IQ associated with OME remained significant to 13 years. The largest effects were observed for deficits in reading ability between 11 and 18 years. CONCLUSIONS: No previous study considering behaviour problems as an outcome has followed children long enough to determine whether some of the early sequelae of OME are still present in the early to late teens. Some developmental sequelae of OME, particularly deficits in reading ability, can persist into late childhood and the early teens.  (+info)

Does early detection of otitis media with effusion prevent delayed language development? (5/154)

OBJECTIVE: To consider whether earlier detection of otitis media with effusion (OME) in asymptomatic children in the first 4 years of life prevents delayed language development. METHODS: MEDLINE and other databases were searched and relevant references from articles reviewed. Critical appraisal and consensus development were in accordance with the methods of the Canadian Task Force on Preventive Health Care. RESULTS: No randomised controlled trials assessing the overall screening for OME and early intervention to prevent delay in acquiring language were identified, although one trial evaluated treatment in a screened population and found no benefit. The "analytic pathway" approach was therefore used, where evidence is evaluated for individual steps in a screening process. The evidence supporting the use of tools for early detection such as tympanometry, microtympanometry, acoustic reflectometry, and pneumatic otoscopy in the first 4 years of life is unclear. Some treatments (mucolytics, antibiotics, steroids) resulted in the short term resolution of effusions as measured by tympanometry. Ventilation tubes resolved effusions and improved hearing. Ventilation tubes in children with hearing loss associated with OME benefited children in the short term, but after 18 months there was no difference in comparison with those assigned to watchful waiting. Most prospective cohort studies that evaluated the association between OME and language development lacked adequate measurement of exposure or outcome, or suffered from attrition bias. Findings with regard to the association were inconsistent. CONCLUSIONS: There is insufficient evidence to support attempts at early detection of OME in the first 4 years of life in the asymptomatic child to prevent delayed language development.  (+info)

Auditory system: Peripheral nonlinearity and central additivity, as revealed in the human stapedius-muscle reflex. (6/154)

Human stapedius-muscle contractions in response to 3-kHz, 20-msec tone bursts were determined indirectly by measuring the associated acoustic-impedance changes at the tympanic membrane with an acoustic bridge. The measurement was possible because the bridge practically eliminates the effect of the ear-canal air volume interposed between the tympanic membrane and the tip of the measuring tube. By using burst pairs, temporal additivity of the muscle responses was demonstrated both when the stimulus bursts were presented contralaterally to the measured impedance changes and when the first burst was presented ipsilaterally. The summation time constant was on the order of 200 msec, much longer than the twitch time constant of the muscle fibers. Therefore, the summation had to take place in a nucleus preceding the stapedius muscle. The magnitude of the muscle response obeyed a compressive function paralleling the loudness function up to sound pressure levels of at least 120 dB.  (+info)

Practical screening priorities for hearing impairment among children in developing countries. (7/154)

Routine screening for hearing impairment in childhood is now widespread in industrial countries, although there is considerable controversy over the most efficient techniques and procedures. In most developing countries, however, routine screening programmes for hearing impairment do not currently exist. The problems involved in implementing screening programmes in developing and industrial countries are very different, and in selecting screening procedures for a particular population the following factors have to be taken into consideration: the environmental test conditions; the availability of resources for equipment and the training of testers; the local attitudes towards disability; the level of hearing impairment that may cause handicaps; and the major types of pathology causing hearing impairment. We suggest that in developing countries children should be screened at school entry using a simple field audiometer and that the external ear be inspected for the presence of a discharge. There is an urgent need to develop reliable and simple screening procedures for infants and young children; where possible, all children should be screened for severe or significant hearing impairment before the age of 2 years. No screening should, however, be implemented until appropriate follow-up services are available.  (+info)

Impedance analysis of the organ of corti with magnetically actuated probes. (8/154)

An innovative method is presented to measure the mechanical driving point impedance of biological structures up to at least 40 kHz. The technique employs an atomic force cantilever with a ferromagnetic coating and an external magnetic field to apply a calibrated force to the cantilever. Measurement of the resulting cantilever velocity using a laser Doppler vibrometer yields the impedance. A key feature of the method is that it permits measurements for biological tissue in physiological solutions. The method was applied to measure the point impedance of the organ of Corti in situ, to elucidate the biophysical basis of cochlear amplification. The basilar membrane was mechanically clamped at its tympanic surface and the measurements conducted at different radial positions on the reticular lamina. The tectorial membrane was removed. The impedance was described by a generalized Voigt-Kelvin viscoelastic model, in which the stiffness was real-valued and independent of frequency, but the viscosity was complex-valued with positive real part, which was dependent on frequency and negative imaginary part, which was independent of frequency. There was no evidence for an inertial component. The magnitude of the impedance was greatest at the tunnel of Corti, and decreased monotonically in each of the radial directions. In the absence of inertia, the mechanical load on the outer hair cells causes their electromotile displacement responses to be reduced by only 10-fold over the entire range of auditory frequencies.  (+info)

Acoustic impedance tests are diagnostic procedures used to measure the impedance or resistance of various parts of the ear to sound waves. These tests are often used to assess hearing function and diagnose any issues related to the middle ear, such as fluid buildup or problems with the eardrum.

The most common type of acoustic impedance test is tympanometry, which measures the mobility of the eardrum and the middle ear system by creating variations in air pressure within the ear canal. During this test, a small probe is inserted into the ear canal, and sound waves are generated while the pressure is varied. The resulting measurements provide information about the condition of the middle ear and can help identify any issues that may be affecting hearing.

Another type of acoustic impedance test is acoustic reflex testing, which measures the body's natural response to loud sounds. This involves measuring the contraction of the stapedius muscle in the middle ear, which occurs in response to loud noises. By measuring the strength and timing of this reflex, audiologists can gain additional insights into the functioning of the middle ear and identify any abnormalities that may be present.

Overall, acoustic impedance tests are important tools for diagnosing hearing problems and identifying any underlying issues in the middle ear. They are often used in conjunction with other hearing tests to provide a comprehensive assessment of an individual's hearing function.

Acoustics is a branch of physics that deals with the study of sound, its production, transmission, and effects. In a medical context, acoustics may refer to the use of sound waves in medical procedures such as:

1. Diagnostic ultrasound: This technique uses high-frequency sound waves to create images of internal organs and tissues. It is commonly used during pregnancy to monitor fetal development, but it can also be used to diagnose a variety of medical conditions, including heart disease, cancer, and musculoskeletal injuries.
2. Therapeutic ultrasound: This technique uses low-frequency sound waves to promote healing and reduce pain and inflammation in muscles, tendons, and ligaments. It is often used to treat soft tissue injuries, arthritis, and other musculoskeletal conditions.
3. Otology: Acoustics also plays a crucial role in the field of otology, which deals with the study and treatment of hearing and balance disorders. The shape, size, and movement of the outer ear, middle ear, and inner ear all affect how sound waves are transmitted and perceived. Abnormalities in any of these structures can lead to hearing loss, tinnitus, or balance problems.

In summary, acoustics is an important field of study in medicine that has applications in diagnosis, therapy, and the understanding of various medical conditions related to sound and hearing.

A transducer is a device that converts one form of energy into another. In the context of medicine and biology, transducers often refer to devices that convert a physiological parameter (such as blood pressure, temperature, or sound waves) into an electrical signal that can be measured and analyzed. Examples of medical transducers include:

1. Blood pressure transducer: Converts the mechanical force exerted by blood on the walls of an artery into an electrical signal.
2. Temperature transducer: Converts temperature changes into electrical signals.
3. ECG transducer (electrocardiogram): Converts the electrical activity of the heart into a visual representation called an electrocardiogram.
4. Ultrasound transducer: Uses sound waves to create images of internal organs and structures.
5. Piezoelectric transducer: Generates an electric charge when subjected to pressure or vibration, used in various medical devices such as hearing aids, accelerometers, and pressure sensors.

Electric impedance is a measure of opposition to the flow of alternating current (AC) in an electrical circuit or component, caused by both resistance (ohmic) and reactance (capacitive and inductive). It is expressed as a complex number, with the real part representing resistance and the imaginary part representing reactance. The unit of electric impedance is the ohm (Ω).

In the context of medical devices, electric impedance may be used to measure various physiological parameters, such as tissue conductivity or fluid composition. For example, bioelectrical impedance analysis (BIA) uses electrical impedance to estimate body composition, including fat mass and lean muscle mass. Similarly, electrical impedance tomography (EIT) is a medical imaging technique that uses electric impedance to create images of internal organs and tissues.

Ultrasonography, also known as sonography, is a diagnostic medical procedure that uses high-frequency sound waves (ultrasound) to produce dynamic images of organs, tissues, or blood flow inside the body. These images are captured in real-time and can be used to assess the size, shape, and structure of various internal structures, as well as detect any abnormalities such as tumors, cysts, or inflammation.

During an ultrasonography procedure, a small handheld device called a transducer is placed on the patient's skin, which emits and receives sound waves. The transducer sends high-frequency sound waves into the body, and these waves bounce back off internal structures and are recorded by the transducer. The recorded data is then processed and transformed into visual images that can be interpreted by a medical professional.

Ultrasonography is a non-invasive, painless, and safe procedure that does not use radiation like other imaging techniques such as CT scans or X-rays. It is commonly used to diagnose and monitor conditions in various parts of the body, including the abdomen, pelvis, heart, blood vessels, and musculoskeletal system.

Impedance plethysmography is a non-invasive method used to measure changes in blood volume or flow in a particular area of the body. It works by passing a small electrical current through the tissue and measuring the opposition (impedance) to that current, which varies with the amount of blood present in the area.

In impedance cardiography, this technique is used to estimate cardiac output, stroke volume, and other hemodynamic parameters. The changes in impedance are measured across the chest wall, which correlate with the ventricular ejection of blood during each heartbeat. This allows for the calculation of various cardiovascular variables, such as the amount of blood pumped by the heart per minute (cardiac output) and the resistance to blood flow in the systemic circulation (systemic vascular resistance).

Impedance plethysmography is a safe and reliable method for assessing cardiovascular function, and it has been widely used in clinical settings to evaluate patients with various cardiovascular disorders, including heart failure, hypertension, and peripheral arterial disease.

Impedance cardiography is a non-invasive method to measure cardiac output and systemic vascular resistance. It uses low-frequency electrical currents passed through the thorax to measure changes in impedance or resistance to flow during each heartbeat. This allows for the calculation of stroke volume and cardiac output. Impedance cardiography can provide continuous, real-time monitoring of cardiovascular function, making it useful in critical care settings and for tracking changes in patients with heart failure or other cardiovascular conditions.

Dielectric spectroscopy is a type of material characterization technique that measures the dielectric properties of a material as a function of frequency. The dielectric property of a material refers to its ability to store electrical energy in the form of polarization when an external electric field is applied. In dielectric spectroscopy, the material's response to an alternating electric field is measured, and the resulting complex permittivity (which includes both real and imaginary components) is used to characterize the material's dielectric behavior.

The technique involves applying a small amplitude AC voltage to the material while measuring the current flow through it. The frequency of the applied voltage can be varied over a wide range, typically from millihertz to gigahertz. By analyzing the phase shift and amplitude of the resulting current, the complex permittivity of the material can be determined as a function of frequency.

Dielectric spectroscopy is widely used in materials science, physics, chemistry, and biology to study the structure, dynamics, and composition of various materials, including polymers, ceramics, glasses, colloids, and biological tissues. The technique can provide valuable information about the material's molecular mobility, relaxation processes, conductivity, and other dielectric properties, which can be used for quality control, process monitoring, and fundamental research.

... otoacoustic emission test, acoustic impedance meter tests, and a speech-language assessment. 12.17% of the children had hearing ... Out of these infants with some hearing impairment, 27 were given the Auditory Brainstem Response Test, in which 80% tested ... All infants received the Otoacoustic Emission Test. It was determined that 9.37% of the infants had some hearing impairment. ... The screening included a preliminary ear checkup, subjective and objective audiometric tests, ...
... but which is at a high acoustic pressure (thus a very high acoustic impedance), is partly converted into audible sound in air ... This is most commonly done with two exams called the Weber test and Rinne test, respectively. Lower-pitched ones, usually at ... If just held in open air, the sound of a tuning fork is very faint due to the acoustic impedance mismatch between the steel and ... thus low acoustic impedance). The pitch of a tuning fork can also be heard directly through bone conduction, by pressing the ...
Acoustic impedance of the embouchure hole appears to be the most critical parameter. Critical variables affecting this acoustic ... Finding a particularly good example of a flute is dependent on play-testing. Head joint upgrades are usually suggested as a way ... "Acoustic impedance of the flute". Flute acoustics: an introduction. "Curved Head Student Flute by Gear4music". Gear4music. 2016 ... However, small deviations from the objective 'mechanical' pitch (which is related to acoustic impedance of a given fingering) ...
The waves reflected at the interface travel back to the transducer, then the acoustic impedance of the sample is determined by ... Applications include medical ultrasonography and nondestructive testing. Neutron reflectometry: is a neutron diffraction ... Acoustic reflectometry: the reflection of sound waves is used. One application is the use of a tympanometer (a specialised ... Teppo, Heikki; Revonta, Matti (2009). "Consumer acoustic reflectometry by parents in detecting middle-ear fluid among children ...
"Bruel & Kjaer - Acoustic/Vibration Testing and Measurement Solutions". Archived from the original on 26 October 2012. Retrieved ... and acoustic panel in situ impedance measurement) It also supplies in-flight engine monitoring with flight-certified, high- ... It also supplies systems for underwater acoustics, shock testing, noise and vibration testing and structural dynamics testing. ... Other systems have tested Astrium's satellite prior to launch, and performed qualification and acceptance testing, such as the ...
... is made of a material having a low acoustic impedance and has a sufficiently thick wall to ensure structural stability. Close- ... Test frequencies ranged from 0.5 Hz to 40 Hz. Test subjects suffered motor ataxia, nausea, visual disturbance, degraded task ... In the proposed test, test parameters will be sensitivity, background noise, signal fidelity (harmonic distortion), and ... These tests are assumed by researchers to be the nucleus of the current urban myth.[clarification needed] The report "A Review ...
... can be sometimes used as replacement for water in ultrasonic testing, as it has favourably higher acoustic impedance ( ... Further testing on this subject was abandoned due to the unexpected results, as this was not the goal of the experiment. ... Glycerol injections can be used as a simple test for liver damage, as its rate of absorption by the liver is considered an ... On 4 May 2007, the FDA advised all U.S. makers of medicines to test all batches of glycerol for diethylene glycol contamination ...
It was found that a layer with high acoustic impedance with a backing of a softer, low acoustic impedance layer (such as low ... Bass et al., 2006, Comparative testing of effectiveness of different helmet/shield designs at reducing head acceleration due to ... similar to the NIJ standards that are widely used to test and compare body armor or materials used to stop ballistic threats. ... it was also shown that it is important to understand the frequency content of the applied blast wave and to experimentally test ...
CSSI transforms seismic data to a pseudo-acoustic impedance log at every trace. Acoustic impedance is used to produce more ... which can then be narrowed through testing for best fit against various measurements (including production data). An example of ... The inversion results in acoustic impedance (AI), which is the product of rock density and p-wave velocity. Unlike seismic ... A good (CSSI) algorithm will produce four high-quality acoustic impedance volumes from full or post-stack seismic data: full- ...
... the use of some type of acoustic coupling medium in order to efficiently transmit the energy from the sensor to the test ... piezoelectric transducer can produce frequencies in the MHz that can easily propagate through even high acoustic impedance ... Non-contact ultrasound (NCU) is a method of non-destructive testing where ultrasound is generated and used to test materials ... However, in non-contact ultrasound, ambient air is the only acoustic coupling medium. An electromagnetic acoustic transducer ( ...
The acoustic (or seismic) impedance, Z, is defined by the equation: Z = v ρ {\displaystyle Z=v\rho \ } , where v is the seismic ... 30 km in areas of seismic testing.[citation needed] Similarly the breathing of gray whales was shown to be more rapid, ... Seismic waves are mechanical perturbations that travel in the Earth at a speed governed by the acoustic impedance of the medium ... Hydrocarbon exploration - used by the hydrocarbon industry to provide a high resolution map of acoustic impedance contrasts at ...
... acoustic impedance almost zero) from inclusions and particles, but not from air bubbles, which show same impedance behavior as ... SAM is highly sensitive to any entrapped air in the sample under testing. In order to enhance the insertion of the acoustic ... the technique registers the echo generated by the acoustic impedance (Z) contrast between two materials. Scanning acoustic ... So, in scanning acoustic microscopy either reflected or transmitted acoustic waves are processed to analyze the internal ...
Moreover, the acoustic performance is linked to the acoustic impedance which can be measured with one of the following ... The acoustic liners' performance can be verified in dedicated experimental test rigs, by means of virtual prototypes or by ... Effects of liner geometry on acoustic impedance. AIAA Paper, 2446, 2002. Dean, P. D.,An In-Situ Method of Wall Acoustic ... Moreover, the in-situ method is the only one able to measure the impedance directly on full scale acoustic liners. Murray, P., ...
... to describe the combined measure of electrical or acoustic admittance and electrical or acoustic impedance. Immittance was ... "Immittance Testing". Sacramento ENT. Retrieved 2023-05-20. "The Immittance Smith Chart - Impedance Matching with only L and C ... Immittance does not have an associated unit because it applies to both impedance, which is measured in ohms (Ω) or acoustic ... This allows for the visualization of changes in impedance or admittance in the system caused by components of either the series ...
A key factor for acoustic band gap engineering is the impedance mismatch between periodic elements comprising the crystal and ... The first successful industrial applications of acoustic metamaterials were tested for aircraft insulation. Properties of ... This concept can be exploited with periodic arrangements of impedance-mismatched elements to affect acoustic waves in the ... With acoustic metamaterials the direction of sound through the medium can be controlled by manipulating the acoustic refractive ...
The test is carried out by generating an acoustic pulse from a speaker or spark source and this sound pulse is transmitted to ... is reflected back to a microphone and this reflection is generated according to the changes in the local acoustic impedance ... O, Hilberg; AC, Jackson; DL, Swift; OF, Pedersen (1989). "Acoustic Rhinomtry: Evaluation of nasal cavity geometry by acoustic ... Acoustic rhinometry is a diagnostic measurement of cross sectional area and length of the nose and the nasal cavity through ...
The Acoustic Test Tank is equipped with the instrumentation required for determining the acoustic characteristics of sonar ... devices designed for frequency response calibrations, radiation pattern plots, and impedance and admittance characterizations. ... Laboratory which houses an array of tanks including an Acoustic Reverberant Tank and an Acoustic Test Tank for acoustic ... ARL operates the Advanced Nuclear Fuel Test Facility (ANFTF) which is a Westinghouse-funded facility to test advanced power ...
Common causes of echo include impedance mismatches in analog circuitry and an acoustic path from the receive to transmit signal ... "Performance and Stress Testing of SIP Servers, Clients and IP Networks". StarTrinity. August 13, 2016. "Testing Voice over IP ( ... The metrics are determined by VoIP performance testing and monitoring. A VoIP media gateway controller (aka Class 5 Softswitch ... "Methodology for SIP Infrastructure Performance Testing" (PDF). Miroslav Voznak, Jan Rozhon. August 14, 2016. "Voice over IP ( ...
An acoustic interferometer is an instrument for measuring the physical characteristics of sound waves in a gas or liquid, such ... It is also used in the testing of optical components. In 1946, a technique called astronomical interferometry was developed. ... velocity, wavelength, absorption, or impedance. A vibrating crystal creates ultrasonic waves that are radiated into the medium ... Interference effects can be observed with all types of waves, for example, light, radio, acoustic, surface water waves, gravity ...
When a wave encounters a change in acoustic impedance, such as hitting a solid surface, acoustic reflections transpire. These ... "Fire Testing Data". auralex.com. Chen, Francine Robina (1980). "Acoustic characteristics and intelligibility of clear and ... Foley, Dennis (2020-02-05). "How Does Acoustic Foam Work?". Acoustic Fields. Retrieved 2020-12-31. "What Is Acoustic Foam Made ... Many acoustic foam products are treated with dyes and/or fire retardants. The objective of acoustic foam is to improve or ...
Ultrasound backscatter uses the variability between acoustic impedance to differentiate between particle versus medium. Such a ... The use of ultrasound to facilitate blood-brain barrier disruption has been tested in animal trials including primates. ... Acoustic waves, often used interchangeably with ultrasound, have been used to irradiate cells and their photoacoustic response ... An example of this is acoustic angiography where FUS is used to reach high resolutions for this technique. Similar studies use ...
... which reflect the sound due to mismatched acoustic impedance. Brown note Directional sound Electronic harassment - Conspiracy ... Tests performed on mice show the threshold for both lung and liver damage occurs at about 184 dB. Damage increases rapidly as ... A long-range acoustic device (LRAD) produces a 30 degree cone of audible sound in frequencies within the human hearing spectrum ... A similar system is called a "magnetic acoustic device". The Mosquito sonic devices have been used in the United Kingdom to ...
... allowing the acoustic transfer impedance Z ac {\displaystyle Z_{\text{ac}}} to be easily modelled. One of the microphones is ... This service is offered by some microphone manufacturers and by independent testing laboratories. Microphone calibration by ... and the acoustical transfer impedance equals the electrical transfer impedance. Z i j = U j I i = M i Z ac M j {\displaystyle Z ... is determined during the calibration procedure by measuring the current and voltage and the acoustic transfer impedance depends ...
These boards were wired at the factory, tested and packaged with the unassembled chassis. It remained only for the consumer to ... The resistant venting action lowered the "Q" of the system and reduced impedance variation near resonance in the A-Series ... whose acoustic resistance is very carefully controlled. ... tested circuit boards that only required the customer to wire ... which generally required the purchaser to assemble and test the PC boards themselves, a relatively precise and time-consuming ...
... hearing tests MeSH E01.370.382.375.050 - acoustic impedance tests MeSH E01.370.382.375.060 - audiometry MeSH E01.370.382.375. ... impedance MeSH E01.370.370.610.610.200 - cardiography, impedance MeSH E01.370.370.750 - tilt-table test MeSH E01.370.372.200 - ... intradermal tests MeSH E01.370.750.300.400 - kveim test MeSH E01.370.750.300.750 - skin test end-point titration MeSH E01.370. ... intradermal tests MeSH E01.450.495.750.300.540 - kveim test MeSH E01.450.495.750.300.750 - skin test end-point titration MeSH ...
Most of the time, the stapedius reflex is tested with tympanometry. The contraction of the stapedius muscle stiffens the middle ... 267-9. ISBN 978-0-07-285293-6. "Impedance Audiometry". MedScape. 2018-09-12. W. Niemeyer (1971). "Relations between the ... the sound used to trigger the acoustic reflex). For most animals, the acoustic reflex is the contraction of both middle ear ... The acoustic reflex threshold (ART) is the sound pressure level (SPL) from which a sound stimulus with a given frequency will ...
A hydrophone can detect airborne sounds, but will be insensitive because it is designed to match the acoustic impedance of ... Bragg tested a hydrophone from a captured German U-boat and found it inferior to British models. By the end of the war, the ... the high acoustic impedance of piezoelectric materials facilitated their use as underwater transducers. The same piezoelectric ... but will give poor performance due to the similarly bad acoustic impedance match. The first hydrophones consisted of a tube ...
The ratio of stress and speed should not be called "acoustic impedance" (in analogy to the mechanical impedance) because this ... One can always test for nonlinear behavior by checking for a dependence of the resonance parameters on the driving voltage. If ... Synonymous terms are "surface impedance" and "acoustic load." The load impedance is in general not equal to the material ... The transformer acts as an impedance converter in the sense that a mechanical impedance, Zm, appears as an electrical impedance ...
However, due to the general equality in acoustic impedance for many types of structures in the breast ultrasound imaging ... DATG is not a test that directly substitutes for other tests, but stands in relation to them as a technique that provides a ... The angiothermography is not a test that substitutes for other tests, but stands in relation to them as a technique that gives ... As such, it has been most successfully employed in combination with other tests to improve the quality of the diagnosis. ...
... so that the resulting sound field contains acoustic energy across the whole audible range. Anechoic chamber, an acoustic test ... The change of impedance (compared to the air) these surfaces present to incident sound is so large that virtually all of the ... an electromagnetic environment mainly for electromagnetic compatibility testing ISO Standard for Measurement of Acoustic ... additional acoustic diffusers are often used to create more reflecting surfaces and further encourage even distribution of any ...
When a sound wave is transferred from a low-impedance medium (eg, air) to one of high impedance (eg, water), a considerable ... The primary function of the middle ear is to offset the decrease in acoustic energy that would occur if the low impedance ear ... canal air directly contacted the high-impedance cochlear fluid. ... Acoustic reflex impedance testing. This is a middle ear ... Tympanotomy impedance testing. This test measures changes in eardrum compliance because air pressure is varied in the external ...
... otoacoustic emission test, acoustic impedance meter tests, and a speech-language assessment. 12.17% of the children had hearing ... Out of these infants with some hearing impairment, 27 were given the Auditory Brainstem Response Test, in which 80% tested ... All infants received the Otoacoustic Emission Test. It was determined that 9.37% of the infants had some hearing impairment. ... The screening included a preliminary ear checkup, subjective and objective audiometric tests, ...
... including in-depth information on acoustic absorption and noise models. ... Impedance testing of a GKN Aerospace zero splice acoustic panel. Control of acoustic absorption is key to producing acceptable ... Portable Impedance Meter Type 9737 is a user-friendly kit for quick, non-destructive acoustic material testing ... on unbonded acoustic materials have been replaced by measurements of the in situ acoustic impedance spectra of the fully bonded ...
Immittance or impedance testing including: Tympanograms, acoustic reflexes, and reflex decay. *Swimmers Ear ... Pediatric Audiology testing including: Behavior Observation testing, Visual reinforcement testing, and Play Audiometry testing ... Diagnostic Audiology testing including: Pure tone air and bone conduction, speech reception threshold, and speech ...
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An ultrasonic test measured time to determine velocity and acoustic impedance later. The results show that increasing the ... This new family of test statistics will be called Wald-type test statistics. The problem of testing a simple and a composite ... The highest acoustic impedance was at 28% UP/PMMA+PS. In conclusion, UP/PMMA+PS can dissipate ultrasonic waves more than UP/ ... Electrochemical impedance spectroscopy test results also demonstrated that the increase in the polarization resistance for ...
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Evaluation of the acoustic and non-acoustic properties of sound absorbing materials using a three-microphone impedance tube ». ... A finite element model to predict the double hearing protector effect on an in-house acoustic test fixture ». The Journal of ... Acoustic radiation of a vibrating wall covered by a porous layer: Transfer impedance concept and effect of compression ». 158th ... An explanation of the decrease in the earplug noise reduction when combined with an earmuff on an acoustic test fixture ». The ...
Acoustic-signals; Impulse-noise; Noise-measurement; Standards; Testing-equipment; Shock-waves; Laboratory-testing; Acoustic- ... An acoustic horn was designed and manufactured to provide impedance matching between the shock tube and the room. The horn ... In-depth survey report: design and construction of an acoustic shock tube for generating high-level impulses to test hearing ... Passive HPDs with a non-linear valve or orifice rely on increased acoustic impedance with an increased pressure differential ...
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  • That frequency can be determined by means of multifrequency tympanometry, a test that can be performed with a middle ear analyzer. (arquivosdeorl.org.br)
  • In a normal-hearing ear, the stapedius muscle in the middle ear contracts involuntarily in response to loud sounds presented at levels of about 70-100 dB (decibels).The primary purpose of impedance audiometry is to determine the status of the tympanic membrane and middle ear via tympanometry. (hearinghealthhhp.com)
  • Who first used the term "tympanometry" to describe the effect of ear canal pressure on impedance? (noblehearinginstitute.com)
  • Tests of the middle ear is further segmented into tympanometry and static acoustic impedance. (articlefloor.com)
  • In addition to traditional audiometry, advanced testing such as acoustic reflex testing, otoacoustic emissions, and impedance tympanometry are available for a more thorough investigation and accurate diagnosis. (memorialvillagesinushearing.com)
  • Tympanometry, acoustic reflectometry, and audiometry are important adjunctive techniques with which to evaluate patients with middle ear effusion (MEE). (medscape.com)
  • To meet this need, Brüel & Kjær has brought to the market a state-of-the-art flanged portable impedance tube, with routines for measurement of panel impedance, non-linearity, and quality control pass/fail tolerances. (bksv.com)
  • CHOBOLA, Z. The determination of measurement errors in impedance spectroscopy. (vutbr.cz)
  • The SIT-system shows up the measurement signal directly on the full colour screen, in order to verify on the spot that tests have been performed correctly. (geonoise.com)
  • Another part of the impedance test battery is acoustic reflex measurement. (hearinghealthhhp.com)
  • Acoustic reflex measurement allows the audiologist to further examine the integrity of the middle ear system. (hearinghealthhhp.com)
  • In many materials like fine grain metals, ceramics, and thin polymers, these higher test frequencies permit measurement of significantly lower thickness limits and detection of significantly smaller flaws and other internal structures as compared to conventional test frequencies of 20 MHz and below. (olympus-ims.com)
  • Middle ear function is then determined by the amount of mobility.The purpose of this study will be to compare two methods far determining middle ear malfunction: acoustic impedance measurement and otoscopic examination. (bsu.edu)
  • The acoustic characterization was feasible by employing the Impedance Tube (IT) method, which is a standardised measurement technique, and the Small-Scaled Reverberation Room (SSRR), located at Politecnico di Torino. (polito.it)
  • In addition, it was shown that sample mounting and fixing conditions during the impedance tube measurement had a strong effect on the determination of the sound absorption coefficient. (polito.it)
  • For physiologic hearing to occur, a precochlear amplification system must be present to address the impedance mismatch that exists between air and water. (medscape.com)
  • If just held in open air, the sound of a tuning fork is very faint due to the acoustic impedance mismatch between the steel and air. (wikipedia.org)
  • IE uses a low-amplitude, high-frequency source (often a spring-loaded or solenoid-driven ball bearing) to obtain a frequency-domain measure of the compression wave's travel time between the outer surface and internal planar discontinuities or external boundaries that exhibit an acoustic impedance mismatch. (cdc.gov)
  • The transducer converts electrical signals into acoustic pulses. (justia.com)
  • Advances in transducer manufacturing technology and associated instrument electronics have led to the introduction of commercial products that provide the capability for ultrasonic imaging, thickness gaging, flaw detection, and material analysis at test frequencies greater than 50 MHz. (olympus-ims.com)
  • 12. Search units with a plastic wedge or standoff between the transducer element and the test piece are used for: A. Straight beam contact testing. (studystack.com)
  • Common measurements include transducer impedance, free-field voltage sensitivity (receive sensitivity), transmitting voltage response (transmit sensitivity), source-level measurements and beam patterns. (unh.edu)
  • Approximate liner DC flow resistance measurements (frequency = 0 Hz) on unbonded acoustic materials have been replaced by measurements of the in situ acoustic impedance spectra of the fully bonded product after all manufacturing processes are complete. (bksv.com)
  • The attenuation effect of water is an additional factor that must be considered in immersion measurements where sound is coupled into a test piece through a water bath or water column. (olympus-ims.com)
  • These clinical acoustic impedance measurements may be classified as either static or dynamic. (bsu.edu)
  • Static acoustic impedance measurements are made with ambient air pressure within the external auditory meatus, while dynamic measurements are made when the air pressure is varied within the external auditory meatus. (bsu.edu)
  • A couple of telephone engineers played an important role by writing about acoustical impedance in both theory and human measurements. (noblehearinginstitute.com)
  • The acoustic test-tank facility is equipped to do standard measurements for hydrophones, projectors, and sonar systems. (unh.edu)
  • This tank is the largest acoustic calibration facility in the Northeast and is well suited for measurements of high-frequency, large-aperture sonars when far-field measurements are desired. (unh.edu)
  • The portable tube measures impedance, a parameter not normally assessed in interior acoustics, where the absorption parameter rules. (bksv.com)
  • In-depth survey report: design and construction of an acoustic shock tube for generating high-level impulses to test hearing protection devices. (cdc.gov)
  • The standard recommends generating the required impulse sound events using explosive charges or an acoustic shock tube. (cdc.gov)
  • Description: This report describes the design and construction of the NIOSH acoustic shock tube. (cdc.gov)
  • An acoustic horn was designed and manufactured to provide impedance matching between the shock tube and the room. (cdc.gov)
  • The modifications to the acoustic shock tube have been incorporated into subsequent versions of the shock tube manufactured and sold by B/C Precision Tool (formerly Cauble Precision Machine Inc.). Conclusions: The NIOSH acoustic shock tube has demonstrated that impulses can be successfully produced using a polyester membrane of thicknesses of 0.001 or 0.002 inch thickness. (cdc.gov)
  • They were tested to investigate their own sound absorbing properties and to understand the relationship between physical parameters and acoustical performance. (polito.it)
  • All infants received the Otoacoustic Emission Test. (wikipedia.org)
  • By product, the market is segmented into otoacoustic emission (OAE)/auditory brainstem response (ABR) testing devices, audiometers, immittance screeners, and others. (articlefloor.com)
  • The OAE/ABR testing devices segment accounted for 67% market share in 2017, followed by audiometers, immittance screeners, and others. (articlefloor.com)
  • Control of acoustic absorption is key to producing acceptable cabin acoustics in cars, trucks, trains, and airplanes as well as for room acoustics. (bksv.com)
  • The acoustic absorption of large samples is typically measured in dedicated reverberation room facilities, while small-scale samples may be cut and inserted into impedance tubes. (bksv.com)
  • ESDU 74003: Normal incidence absorption coefficients and acoustic impedances of typical single layer fibrous lining materials. (esdu.com)
  • Normal incidence absorption coefficients and acoustic impedances of typical single layer fibrous lining materials. (esdu.com)
  • The absorption coefficients and impedances are estimated for noise environments up to 160 dB in the absence of flow. (esdu.com)
  • The absorption coefficient is a function of the physical properties of the liner, and the impedance a function of both the liner physical properties and the noise environment. (esdu.com)
  • Both were chosen to determine the sound absorption coefficient, that is one of the most representative parameters defining the sound absorbing material quality as it can measure the quantity of the sound energy absorbed from the tested sample to the ones hitting its surface. (polito.it)
  • Thus, such experimental results can be considered as initial guidelines in choosing prototypes as potential acoustic systems aimed to the EQ Project as well as an interesting starting point for research and development in sound solutions whose absorption performance could be connected to their mix design characteristics. (polito.it)
  • These include echo recovery time as determined by center frequency and bandwidth, relative sensitivity, beam diameter, focal zone, and attenuation effects in water paths and test materials. (olympus-ims.com)
  • Knowledge of how these factors interact and how they will affect echo response from typical test targets is important for optimizing resolution and sensitivity in very high frequency work. (olympus-ims.com)
  • This paper also includes examples of specific test applications utilizing the frequency range from 50 MHz to 225 MHz. (olympus-ims.com)
  • In any ultrasonic test, it is necessary to consider how the physical properties of the test material will affect sound transmission, and this becomes increasingly important as frequency increases. (olympus-ims.com)
  • Attenuation and scattering in the test material are frequently limiting factors in very high frequency testing, typically restricting its use to applications involving relatively thin materials with good sound transmission properties, and making use of very high frequencies impractical in situations involving thick test pieces or materials that exhibit high levels of ultrasonic attenuation or scattering, such as soft polymers and coarse grain cast metals. (olympus-ims.com)
  • 2] For a given material at a given temperature, tested at a given frequency, there will be a specific attenuation coefficient, commonly expressed in Nepers per centimeter (Np/cm). (olympus-ims.com)
  • While attenuation effects can be a factor in any ultrasonic test, they can be especially dramatic at high frequencies, and the selection of an optimum test frequency must take this into account. (olympus-ims.com)
  • As a practical matter, the maximum test frequency in a given application will always be limited by low pass filtering effects in the test material. (olympus-ims.com)
  • 4. When testing a plate, increasing the frequency of an ultrasonic longitudinal wave will result in: A. an increase in its velocity. (studystack.com)
  • As impact-generated vibrations interact with nearby low-stiffness fracture interfaces and imperfect interfaces between rock layers, loose blocks of rock resonate weakly and produce airborne sound through seismic-acoustic wave conversion. (cdc.gov)
  • 2009). To evaluate the economic potential of gas hydrates in this environment, a test site at Mallik, Northwest Territories, Canada, was extensively surveyed (three-dimensional seismic, full set of logs in two wells, etc.) and a production test was realized in high gas-hydrate horizons. (uspermafrost.org)
  • At Mallik, high P- and S-wave velocities, high acoustic impedances, and strong seismic amplitude reflections were all linked to sand-rich sediments with a high saturation of gas hydrates (Bellefleur et al. (uspermafrost.org)
  • After illustrating the techniques in time-harmonic acoustic problems with different boundary conditions and in electrical impedance tomography problems with continuous Neumann conditions, we extend the hybrid method for a realistic model in tomography where the boundary conditions are given at a discrete set of electrodes. (projecteuclid.org)
  • Typically a change in the characteristic impedance occurs at such a boundary. (justia.com)
  • While TOF has have been used to evaluate changes in thickness, velocity, density, and acoustic impedance, reflected signal amplitude has been used to analyze attenuation, or loss, through a test specimen. (rutgers.edu)
  • In addition to developing techniques for determining individual defect size distributions within a bulk specimen, histogram simulations have been explored to study amplitude and TOF distribution trends by analyzing how the addition of defects of varying size, quantity, and acoustic impedance affect histogram characteristics. (rutgers.edu)
  • 1.The reference holes in standard area-amplitude ultrasonic test blocks contain: A. flat-bottomed holes. (studystack.com)
  • PLŠKOVÁ, I. Nonlinear Acoustic Spectroscopy Method for Nondestructive Testing of Thermally Damaged Concrete. (vutbr.cz)
  • A. Carpio, M.-L. Rapún "Hybrid Topological Derivative-Gradient Based Methods for Nondestructive Testing," Abstract and Applied Analysis, Abstr. (projecteuclid.org)
  • Testing can point out which piles require further examination. (geonoise.com)
  • The present invention relates generally to medical diagnosis and more particularly to the non-destructive testing and non-invasive examination of soft-tissue and body organs using ultrasonic diagnostic equipment. (justia.com)
  • Apparatus and techniques which permit the non-destructive testing and non-invasive examination of soft tissue and body organs are of particular interest to the medical community. (justia.com)
  • Echoes occur at the boundaries between different tissues within the body since a fraction of the incident energy is deflected whenever the characteristic impedance of the structure under examination changes. (justia.com)
  • Those who failed one of the tests were considered to have failed the examination. (bvsalud.org)
  • Ultragel® II is an industry-leading, high-performance, ultrasonic couplant for flaw detection and sizing, thickness gauging, flow metering and acoustic emission testing. (jwjndt.com)
  • We check and compare all kinds of meshes in their structure and design and can therefore define differences or similarities among the respective products through tolerances and adjusted testing intervals. (gkd-group.com)
  • The primary function of the middle ear is to offset the decrease in acoustic energy that would occur if the low impedance ear canal air directly contacted the high-impedance cochlear fluid. (medscape.com)
  • Who was the Nobel Prize recipient who measured the acoustic impedance of the ear with varying ear canal air pressures? (noblehearinginstitute.com)
  • [4] Bone conduction using a tuning fork is specifically used in the Weber and Rinne tests for hearing in order to bypass the middle ear . (wikipedia.org)
  • By test, it is segmented into pure-tone test, bone conduction test, tests of the middle ear, speech discrimination test, speech recognition threshold test, most comfortable listening (MCL) test, and uncomfortable loudness level (UCL)test. (articlefloor.com)
  • Liquid penetration testing is used to inspect various opening defects on the surface of castings, such as surface cracks, surface pinholes and other defects that are difficult to find with the naked eye. (tjdecho.com)
  • Techniques for detecting defects in concrete structures include impulse response (IR) [3] and impact-echo (IE) [4] testing and modal analysis. (cdc.gov)
  • Dr. Piervincenzo Rizzo is a Professor with expertise in nondestructive evaluation and structural health monitoring using acoustic emission, ultrasonic testing, guided waves, electromechanical impedance, and thermography. (pitt.edu)
  • This study presents an acoustic metasurface (AM) consisting of coupled Helmholtz resonators with extended necks (HRENs) to effectively absorb broadband sound waves at both low and high amplitudes. (researchgate.net)
  • For example, read on for the highlights from two white papers examining how noise models are validated for military aircraft, and how commercial aircraft manufacturers are using a new method to measure the noise impedance in the acoustic panels that line engine ducts. (bksv.com)
  • BODNÁROVÁ, L. Classification of Thermally Degraded Concrete by Acoustic Resonance Method and Image Analysis via Machine Learning. (vutbr.cz)
  • CHOBOLA, Z. Effect of Thermal Loading on Selected Parameters of Reinforced Concrete Obtained by Acoustic NDT Method. (vutbr.cz)
  • In order to accurately assess the performance of these types of protectors, the American National Standards Institute revised the ANSI/ASA S12.42 (ANSI, 2010) standard to include a method to measure the impulse peak insertion loss of all hearing protectors over a wide range of impulse levels using a dual-ear acoustic test fixture and a field microphone. (cdc.gov)
  • Sonic Integrity Testing is a widely used method for testing the quality of concrete piles in a non-destructive way before they are incorporated in the final foundation plan. (geonoise.com)
  • Acoustic impedance testing is an objective method for determining middle ear function. (bsu.edu)
  • 8. The depth of a discontinuity cannot be determined when using: A. Straight beam testing method. (studystack.com)
  • B. Through transmission testing method. (studystack.com)
  • C. Angle beam testing method. (studystack.com)
  • D. Immersion testing method. (studystack.com)
  • A nonlinear acoustic model is proposed to characterize the AM performance based on the equivalent medium theory and the transfer matrix method. (researchgate.net)
  • ESDU 74003 gives a method of estimating these acoustic properties of fibremetals and polyimide laminates used to line aircraft propulsion ducts. (esdu.com)
  • The method has been proved against test data for frequencies of 1 to 6.5 kHz, for air gaps of 0.25 to 2 in (6 to 50 mm), for liner thicknesses up to 0.06 in (1.5 mm) and porosities (that is, one minus the ratio of material density to fibre density) of 0.8 and for normal temperature and pressure. (esdu.com)
  • There are two types of eddy current testing: the placement coil method and the through coil method. (tjdecho.com)
  • Thus by pressing the tuning fork's base against a sound board such as a wooden box, table top, or bridge of a musical instrument, this small motion, but which is at a high acoustic pressure (thus a very high acoustic impedance ), is partly converted into audible sound in air which involves a much greater motion ( particle velocity ) at a relatively low pressure (thus low acoustic impedance). (wikipedia.org)
  • Such an aid to diagnosis of middle ear pathology and application to clinical audiology was first realized by Metz (1946).Acoustic impedance measures the opposition encountered by an acoustic wave. (bsu.edu)
  • begingroup\$ Speaker models can actually get quite complicated if you transform the acoustic radiation impedance back into the electrical domain. (stackexchange.com)
  • [ 1 ] When a sound wave is transferred from a low-impedance medium (eg, air) to one of high impedance (eg, water), a considerable amount of its energy is reflected and fails to enter the liquid. (medscape.com)
  • CHOBOLA, Z. The Possibility of Using Nonlinear Acoustic Spectroscopy with a Single Excitation Signal for Testing of Concrete Elements Damaged by High Temperature. (vutbr.cz)
  • The right side features a Kensington lock, two high impedance TS line/instrument inputs and two (high and low impedance) headphone outputs. (prorec.com)
  • Standardized testing procedures on the basis of normative directives guarantee a high degree of quality assurance for existing products, while also providing valuable support in improving existing products and developing new products. (gkd-group.com)
  • Currently, BASWA acoustic works in such direction, providing high-quality acoustic systems whose technology combines functionality and aesthetics, being adaptable to any type of environment. (polito.it)
  • The secondary purpose of this test is to evaluate acoustic reflex pathways, which include cranial nerves (CN) VII and VIII and the auditory brainstem. (hearinghealthhhp.com)
  • Impedance is defined as the product of the density of the tissue multiplied by the velocity of sound. (justia.com)
  • Usually the best way to establish the limits imposed by attenuation and scattering in a specific test situation is by experimentation. (olympus-ims.com)
  • The test object provides for the determination of elevational resolution. (justia.com)
  • Additionally, the test object provides for the determination of the existence, location, intensity and width of side lobes, both substantially in the direction of the scanning plane and in substantially the direction normal to the scanning plane. (justia.com)
  • The ANSI/ASA S12.42-2010 requires that impulse tests be performed at three ranges of impulse peak sound pressure levels. (cdc.gov)
  • The transmission of sound from the ear canal to the cochlea is mediated by the ossicular mass, stiffness of the tympanic membrane, the ligaments and tendons that support the middle ear, air, and by friction, all of which generate a rate of impedance to the sound that reaches the cochlea. (arquivosdeorl.org.br)
  • That test showed that a heavier barrier is better at stopping sound propagation - the driver and microphone were on opposite sides of the materials. (hackaday.com)
  • A fairer test for reducing echos requires reflecting the sound off the surface. (hackaday.com)
  • The magnitude of the reflected sound energy is a function of the directivity and properties of the inner surface or defect and the acoustic impedance of this reflector. (tjdecho.com)
  • In detail, the EQ project is designed to develop an economically competitive sound absorbing system in emerging markets where the price of BASWA standard acoustic systems does not allow them to compete with other manufacturers ones who sell their cheap but low technically level products. (polito.it)
  • 200 cells/L or clinical stage 3 or 4 were enrolled and received CrAg tests on whole blood specimens from August 2018 to August 2019. (cdc.gov)
  • Hospitalized PLHIV were enrolled and tested for CrAg from January 2019 to August 2019, regardless of CD4 or clinical stage. (cdc.gov)
  • 7. If a 3'' discontinuity in a 6'' thick plate lies parallel to the entry surface , it will be best detected by: A. a straight beam test. (studystack.com)
  • C. a surface wave test. (studystack.com)
  • C. Surface wave contact testing. (studystack.com)
  • It should be pointed out that the accuracy of penetrant detection decreases with the increase of the surface roughness of the tested material, that is, the lighter the surface, the better the detection effect, and the surface detection accuracy of the grinding machine is the best, and even intercrystalline cracks can be detected. (tjdecho.com)
  • The main objective of this study was to develop an acoustic plaster based on organic aggregates, as cellulose, in combination with additives and a formulation of organic/inorganic binders. (polito.it)
  • MAIN OBJECTIVE: A cohort of adult Malawian people living with HIV (PLHIV) testing positive for cryptococcal antigenemia was observed and followed to determine the outcomes and risk factors for attrition. (cdc.gov)
  • Initially, Airbus used simple analytical models to quantify source strengths and directivities, but in order to get accurate predictions from the models, a test-based calibration must be performed. (bksv.com)
  • In 2003, with funding from NSF and NOAA, an acoustic calibration facility was added to the engineering tank. (unh.edu)
  • Passive HPDs with a non-linear valve or orifice rely on increased acoustic impedance with an increased pressure differential across the two sides of the orifice or valve. (cdc.gov)
  • STONIŠ, P. Verification of the ability of selected acoustic methods to detect the amount of steel fibers in concrete. (vutbr.cz)
  • CHOBOLA, Z. Monitoring of Thermal Damage Evolution in Concrete Parts by Acoustic NDT Methods. (vutbr.cz)
  • CHOBOLA, Z. Detection of Concrete Thermal Load Time by Acoustic NDT Methods. (vutbr.cz)
  • This will be done by testing patients with middle ear pathologies using both methods and comparing the test results with the surgically-confirmed results. (bsu.edu)
  • For operational ease in developing and testing the proposed methods, a damaged concrete slab was selected to serve as a convenient analog to the blocky roof rock structure encountered in underground mines. (cdc.gov)
  • The eddy current will Generate a magnetic field opposite to the direction of the exciting magnetic field, so that the original magnetic field in the coil is partially reduced, which causes the change of the coil impedance. (tjdecho.com)
  • Acoustic panels line aero-engine ducts to reduce radiated noise levels, and quality control of these panels is under ever-increasing scrutiny. (bksv.com)
  • The word "impedance" was coined by this person, who wrote: "Let us call the ratio of the impressed force to the current…the impedance of the line, from the verb impede… (Put the accent on the middle e in impedance. (noblehearinginstitute.com)
  • If no middle ear were present, only 0.1% of the acoustic wave energy traveling through air would enter the fluid of the cochlea and 99.9% would be reflected. (medscape.com)
  • Similarly, the pure-tone test segment is divided into visual reinforcement and conditioned play audiometries respectively. (articlefloor.com)
  • Proper impedance matching requires the normal anatomy and functioning of an external ear and a middle ear with an intact tympanic membrane, a normal ossicular chain, and a well-ventilated tympanic cavity. (medscape.com)
  • The external and middle ear systems vary significantly in their acoustic response properties over the first 2 years after birth (17). (arquivosdeorl.org.br)
  • For this test, very brief, somewhat loud tones are presented to each ear, to determine whether an acoustic reflex is present or absent, without requiring any response from the patient. (hearinghealthhhp.com)
  • Auditory Late Responses (ALR) assess central auditory processing by neuroelectric activity of the auditory pathway in response to an acoustic stimulus or event. (bvsalud.org)
  • Sonic Integrity Testing (SIT) of concrete piles Pile quality is often determined by performing a low strain integrity test directly after pile driving or within days after installation of cast-in-situ piles. (geonoise.com)
  • The Profound SIT-series meets the constructions industry's demand for professional Sonic Integrity Testing of concrete piles. (geonoise.com)
  • Dr. Lev Khazanovich is a Professor who has been involved in various aspects of concrete pavement research, design and evaluation, including performance prediction modeling, non-destructive testing, and finite element modeling. (pitt.edu)
  • A unique challenge of the urban air mobility noise assessment is the configuration-dependent acoustic signature of different designs, of which the installed noise sources must be considered. (researchgate.net)
  • All business segments in the GKD Group and its customers benefit from the laboratory's material and testing expertise, as well as the experience of professional partners from the fields of testing technology and science. (gkd-group.com)
  • Comparative material testing of this kind allows the quality of our meshes to be optimized for all applications requiring a consistent quality standard. (gkd-group.com)
  • The closer the impedance of the material is to air, the easier it is to couple into it without reflection. (hackaday.com)
  • For this reason, simple test objects have been devised in recent years to measure beam parameters. (justia.com)
  • In such cases, values closest to their average and values based on testing of the most current grades of materials are selected to provide readers with information that is characteristic of currently available products, focusing on the potential use of data in solving practical problems. (chemtec.org)
  • For better acoustic properties, use Owens Corning 703 fiberglass. (hackaday.com)
  • The data obtained proved that components in plaster formulation, such as inorganic fillers and different binder ratios, affected the plaster acoustic properties. (polito.it)